The proposed program represents the continuation of a long term research effort directed toward studying the interaction of ultrasound with tissue and using this knowledge to establish new and improved techniques for ophthalmic diagnosis. The major objectives for the proposed grant period are to evaluate the effectiveness with which tissue characterization schemes based on the spectral properties and the impedance properties of tissue can be utilized to improve ophthalmic diagnosis. More specifically, the following four tasks will be undertaken: (1) An extensive clinical evaluation of spectra-color ultrasonography will be conducted. Spectra-color ultrasonography is a technique for incorporating frequency information into a B-scan ultrasonogram. (2) The spectra-color system will be optimized for diagnostic effectiveness using the results of model experiments and clinical findings. (3) Complementary techniques for the display of spectral information, including real-time spectrum analysis, will be evaluated and compared with spectra-color ultrasonography. (4) Impediography, a time-domain characterization of system dynamics based on the impulse response function, will be investigated as a means for tissue characterization. In summary, the proposed program seeks, through various signal processing and analysis techniques, to extract additional information from an ultrasonic echo waveform and to evaluate the efficacy of such additional information to an improved ophthalmic diagnosis.